The present invention is in the field of terminal position assurance (TPA) devices, used in electrical connector terminals to securely lock inserted wire terminals in their cavities.
Terminal position assurance (TPA) devices are used in the electrical connector art to secure inserted wire harness terminals in their connector cavities, in proper position for electrically mating with the terminals from a mating connector or other electrical component. The TPA devices are often formed separately from the connector and are secured to the connector only after all terminals have been inserted into the connector. Such TPA devices have the usual disadvantages associated with having to provide multiple parts to an assembly station, such as misplaced parts and the problem of separate parts being dropped into inaccessible or sensitive locations.
In addition to their terminal-securing function, TPA devices are also typically designed to provide tactile and visual indication of an insufficiently inserted terminal. This is usually achieved by structuring the TPA device such that it cannot be fully engaged with the connector due to interference from an improperly inserted terminal.
TPA-type devices have also been referred to as terminal locking blocks, terminal detecting members, and connector covers. This list is not exhaustive, but is indicative of the variety of devices which perform the terminal locking and/or detecting functions described above. Some types of TPA devices operate in hinged fashion, some in sliding fashion. Some TPA-type devices may even be formed integrally with the connector body, rather than formed separately. Among those TPA-type devices formed separately from the connector body, many are designed to be attached to the connector body in a position adapted to allow the terminals to be inserted while the TPA-type device remains attached to the connector body.
In general, TPA-type devices require relatively complicated molding or manufacturing processes because of the many interacting attachment and terminal-engagement features, and further to accommodate different motions such as the initial attachment of the TPA-type device to the connector body and the subsequent movement of the TPA between pre-engagement and terminal locking positions. For example, hinged terminal-retaining covers or TPA devices require both hinge structure and latch structure to keep the attached covers from interfering with terminal insertion, to place them in a terminal-engaging position after terminal insertion, and to secure them in the terminal-engaging position.
The present invention is a lengthwise TPA device in combination with an electrical connector especially formed to receive the TPA device in a first pre-engagement condition in which the TPA device is securely attached to the connector at both ends with an intermediate locking projection extending through a slot in the connector. More particularly, in the pre-engagement condition, the TPA is locked at its front end to a front end of the connector, while the rear end of the TPA device is pre-attached to a rearward portion of the connector in a semi-locked state. In this semi-locked state the rear end of the TPA is allowed a limited range of motion away from the terminals, while motion toward its fully locked position is resisted by locking structure on the TPA.
The connector body can be molded by straight action molding with elongated lengthwise slots extending through the connector from its outer, TPA-receiving surface into the terminal cavities. The TPA is provided with intermediate terminal-securing projections or xe2x80x9cblocksxe2x80x9d which, when the TPA is fully engaged to secure the terminals, extend through the slots in the connector body to abut rear portions of the forward terminal ends or xe2x80x9cbarrelsxe2x80x9d inserted in the connector cavities.
The TPA device is formed from a reasonably flexible plastic material, thereby allowing it to flex as it is installed on the connector body in the pre-engagement position, and as it is further snapped into its final, terminal-securing position. The flexible nature of the TPA and the unique blocking and pre-attachment structure at either end of the TPA allows the TPA to be initially assembled, preengaged, and moved to the final terminal-securing position in the manner of a more conventional hinged or rotatable TPA-type device, but with a positive axial lock at both ends to eliminate the possibility of accidental displacement from the terminal-securing position. Further, the semi-locked condition of the TPA terminal insertion end ensures that the terminal insertion end remains open to receive terminals until deliberately locked down.
These and other features and advantages of the invention will become apparent upon further reading of the specification, in light of the accompanying drawings.